I have a fireplace on a raised platform that I'm re-tiling and I want to put ceramic tile on the face of the platform, around 4" high. What type of adhesive/mortar do I need? Is the hardwood the problem or the nearby heat?

Is this a zero clearance fireplace? I am concerned that you have hardwood anywhere near it... even if tiled over.

Is this a zero clearance fireplace?

No, it's a free-standing unit.

Someone jump in with the right info... but I don't think you can have wood anywhere within 1' of the fireplace: